/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.jasper.compiler;

import org.apache.jasper.JasperException;

import javax.servlet.jsp.tagext.TagVariableInfo;
import javax.servlet.jsp.tagext.VariableInfo;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * Class responsible for determining the scripting variables that every
 * custom action needs to declare.
 *
 * @author Jan Luehe
 */
class ScriptingVariabler {

	private static final Integer MAX_SCOPE = Integer.valueOf(Integer.MAX_VALUE);

	public static void set(Node.Nodes page, ErrorDispatcher err)
			throws JasperException {
		page.visit(new CustomTagCounter());
		page.visit(new ScriptingVariableVisitor(err));
	}

	/*
	 * Assigns an identifier (of type integer) to every custom tag, in order
	 * to help identify, for every custom tag, the scripting variables that it
	 * needs to declare.
	 */
	static class CustomTagCounter extends Node.Visitor {

		private int count;
		private Node.CustomTag parent;

		@Override
		public void visit(Node.CustomTag n) throws JasperException {
			n.setCustomTagParent(parent);
			Node.CustomTag tmpParent = parent;
			parent = n;
			visitBody(n);
			parent = tmpParent;
			n.setNumCount(Integer.valueOf(count++));
		}
	}

	/*
	 * For every custom tag, determines the scripting variables it needs to
	 * declare.
	 */
	static class ScriptingVariableVisitor extends Node.Visitor {

		private ErrorDispatcher err;
		private Map<String, Integer> scriptVars;

		public ScriptingVariableVisitor(ErrorDispatcher err) {
			this.err = err;
			scriptVars = new HashMap<String, Integer>();
		}

		@Override
		public void visit(Node.CustomTag n) throws JasperException {
			setScriptingVars(n, VariableInfo.AT_BEGIN);
			setScriptingVars(n, VariableInfo.NESTED);
			visitBody(n);
			setScriptingVars(n, VariableInfo.AT_END);
		}

		private void setScriptingVars(Node.CustomTag n, int scope)
				throws JasperException {

			TagVariableInfo[] tagVarInfos = n.getTagVariableInfos();
			VariableInfo[] varInfos = n.getVariableInfos();
			if (tagVarInfos.length == 0 && varInfos.length == 0) {
				return;
			}

			List<Object> vec = new ArrayList<Object>();

			Integer ownRange = null;
			Node.CustomTag parent = n.getCustomTagParent();
			if (scope == VariableInfo.AT_BEGIN
					|| scope == VariableInfo.AT_END) {
				if (parent == null)
					ownRange = MAX_SCOPE;
				else
					ownRange = parent.getNumCount();
			} else {
				// NESTED
				ownRange = n.getNumCount();
			}

			if (varInfos.length > 0) {
				for (int i = 0; i < varInfos.length; i++) {
					if (varInfos[i].getScope() != scope
							|| !varInfos[i].getDeclare()) {
						continue;
					}
					String varName = varInfos[i].getVarName();

					Integer currentRange = scriptVars.get(varName);
					if (currentRange == null ||
							ownRange.compareTo(currentRange) > 0) {
						scriptVars.put(varName, ownRange);
						vec.add(varInfos[i]);
					}
				}
			} else {
				for (int i = 0; i < tagVarInfos.length; i++) {
					if (tagVarInfos[i].getScope() != scope
							|| !tagVarInfos[i].getDeclare()) {
						continue;
					}
					String varName = tagVarInfos[i].getNameGiven();
					if (varName == null) {
						varName = n.getTagData().getAttributeString(
								tagVarInfos[i].getNameFromAttribute());
						if (varName == null) {
							err.jspError(n,
									"jsp.error.scripting.variable.missing_name",
									tagVarInfos[i].getNameFromAttribute());
						}
					}

					Integer currentRange = scriptVars.get(varName);
					if (currentRange == null ||
							ownRange.compareTo(currentRange) > 0) {
						scriptVars.put(varName, ownRange);
						vec.add(tagVarInfos[i]);
					}
				}
			}

			n.setScriptingVars(vec, scope);
		}
	}
}
